ci: Support joining sdkconfig.ci files that don't end in a newline
ci: Support joining sdkconfig.ci files that don't end in a newline

If trailing newline is missing, the last line of that item gets merged
with the first line of the next item.

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf